This invention relates to the production of bipolymers and more particularly to an improved process for the production of a heteropolysaccharide by action of a microorganism of the species Methylomonas mucosa.
U.S. Pat. No. 3,878,045 to Tannahill et al. discloses a method of preparing a biopolymer by the culturing of a heteropolysaccharide producing strain of the species Methylomonas mucosa in an aqueous culture medium containing methanol. The Tannahill et al. patent refers to application Ser. No. 364,559, filed May 29, 1973, now U.S. Pat. No. 3,923,782 by Finn et al. for a description of the heteropolysaccharide and its method of preparation. The biopolymer and its preparation are also disclosed in the Masters Theses presented to the faculty of the Graduate School of Cornell University by Joseph Edward Laptewicz, Jr., August 1972, entitled "BIOPOLYMER FROM A METHANOL-UTILIZING BACTERIUM" and by John Charles Martin, January 1974, entitled "BATCHWISE PRODUCTION OF BIOPOLYMER FROM METHANOL FERMENTATION".
As disclosed in the Tannahill et al. patent, the culture medium contains inorganic salts providing sources of phosphate, nitrate, sulfate, iron, calcium, magnesium, and zinc. Phosphate is added to the medium in the form of monobasic potassium phosphate and dibasic sodium phosphate. The desirability of maintaining adequate levels of soluble iron for biomass and biopolymer production is recognized by the patentees. Thus they suggest the use of various chelating agents such as ethylenediaminetetraacetic acid in order to enhance the availability of the iron for action by the microorganism. Tannahill et al. also disclose that the pH of the culture medium should be controlled within a relatively narrow range. The patentees indicate that no growth occurs at pH levels below 5.7 or above 8.0 and that a pH range of about 6-7.8 is preferred for growth of the microorganism.